/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   malloc.c                                           :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: tomoron <tomoron@student.42angouleme.fr>   +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2024/11/23 17:19:59 by tomoron           #+#    #+#             */
/*   Updated: 2024/11/29 18:48:26 by tomoron          ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "includes/malloc.h"
#include <stdio.h>
#include <errno.h>
#include <string.h>

void *get_memory(size_t size)
{
	void *ptr;
	t_mem_bloc *bloc_info;

	ptr = mmap(0, size, PROT_WRITE | PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
	if(ptr == MAP_FAILED)
		return(0);
	bloc_info = ptr;
	bloc_info->space_left = size - sizeof(t_mem_bloc);
	bloc_info->next = 0;
	return(ptr);
}

void *allocate_memory(size_t size, t_mem_bloc **bloc)
{
	t_mem_bloc *new;

	new = get_memory(size + sizeof(t_mem_bloc));
	if(!new)
		return(0);
	new->next = *bloc;
	*bloc = new;
	return((char *)new + sizeof(t_mem_bloc));
}

t_alloc *reserve_addr(t_alloc *addr, size_t size, t_alloc *prev, t_mem_bloc *bloc)
{
	t_alloc *tmp;

	if((unsigned long)addr % 16)
		addr = (t_alloc *)((char *)addr + (16 - ((unsigned long)addr % 16))); //O_O
	addr->size = size;
	bloc->space_left -= (size + sizeof(t_alloc));
	if(prev)
	{
		tmp = prev->next;
		prev->next = addr;
		addr->next = tmp;
	}
	else
		addr->next = 0;
	return(addr + 1);
}

t_alloc *get_suitable_addr_in_bloc(t_mem_bloc *bloc, size_t size)
{
	t_alloc *tmp;
	size_t space_left;
	size_t free_space;

	tmp = (void *)bloc + 16;
	space_left = bloc->space_left;
	while(tmp->next)
	{
		free_space = (tmp->next - tmp) - (tmp->size + sizeof(t_alloc)); //what
		if(free_space >= size + sizeof(t_alloc))
			return(reserve_addr(
				(t_alloc *)((char *)tmp->next + tmp->size + sizeof(t_alloc)),
				size, tmp, bloc)); // should be after
		space_left -= free_space;
	}
	if(space_left >= size + sizeof(t_alloc))
		return(reserve_addr(
			(t_alloc *)((char *)tmp + tmp->size + sizeof(t_alloc)),
			size, tmp, bloc)); //not sure about this function
	return(0); //30 minutes later, I don't understand this
}

t_mem_bloc *create_new_bloc(int is_small,t_mem_bloc **bloc, t_mem_bloc *prev)
{
	t_mem_bloc *new;
	size_t mmap_size;

	if(is_small)
		mmap_size = SMALL_BLOC_SIZE;
	else
		mmap_size = TINY_BLOC_SIZE;
	new = get_memory(mmap_size);
	if(!new)
		return(0);
	if(prev)
		prev->next = new;
	if(!*bloc)
		*bloc = new;
	return(new);
}

void *pre_allocated(size_t size, t_mem_bloc **bloc, int is_small)
{
	t_mem_bloc *tmp;
	t_mem_bloc *prev;
	t_alloc *res;
	
	tmp = *bloc;
	prev = *bloc;
	res = 0;
	while(tmp)
	{
		if(tmp->space_left >= size)
		{
			res = get_suitable_addr_in_bloc(tmp, size);
			if(res)
				return(res);
		}
		prev = tmp;
		tmp = tmp->next;
	}
	tmp = create_new_bloc(is_small, bloc, prev);
	if(!tmp)
		return(0);
	return(reserve_addr((void *)tmp + sizeof(t_mem_bloc), size, 0, tmp));
}

void *ft_malloc(size_t size)
{
	if(size <= TINY_MALLOC)
		return(pre_allocated(size, &(g_allocs.tiny), 0));
	else if(size <= SMALL_MALLOC)
		return(pre_allocated(size, &(g_allocs.small), 1));
	else
		return(allocate_memory(size, &(g_allocs.large)));
}

int main(void)
{
	void *ptr;
	void *ptr2;

	ptr = ft_malloc(10);
	ptr2 = ft_malloc(2000);
	printf("%p\n", ptr);
	printf("%p\n", ptr2);
}